defibrillating

Defibrillating is the medical procedure of delivering a controlled electrical shock to the heart with the aim of restoring a normal heart rhythm, typically in cases of certain life-threatening arrhythmias such as ventricular fibrillation or pulseless ventricular tachycardia. The shock depolarizes a critical mass of the heart muscle, halting disordered electrical activity and allowing the heart's natural pacemaker to reestablish a synchronized rhythm.

Defibrillation can be delivered externally, using paddles or pads connected to a defibrillator, or internally via implanted devices. External defibrillators include manual defibrillators used by trained personnel and automated external defibrillators (AEDs) available in public settings. Internal defibrillation is performed by implanted cardioverter-defibrillators (ICDs) that monitor heart rhythm and deliver shocks as needed, without external assistance.

The effectiveness of defibrillation depends on factors such as the underlying rhythm, the duration of the arrest, and the promptness of treatment. Survival rates improve when defibrillation occurs early, ideally within minutes of collapse, and are supported by high-quality chest compressions until a shock can be delivered. Biphasic shock waveforms are commonly used today and are associated with lower energy requirements and greater success than older monophasic waveforms.

Risks include chest burns, myocardial injury, arrhythmias, and, rarely, damage to surrounding tissues. Defibrillation is not appropriate for all rhythms; it is ineffective in asystole and not indicated when there is no electrical cardioversion needed. Training in the use of AEDs and CPR is encouraged for laypersons, while professional guidelines govern the use of external and implanted devices.